Butadiene-styrene copolymer-cement composition and method of preparation

ABSTRACT

1. A cement .Iadd.mortar .Iaddend.composition comprising a mixture of Portland cement, mineral aggregate, about 5%-25% based on the weight of said Portland cement of styrene-butadiene-1,3 copolymer having a styrene to butadiene weight ratio of about 30:70 to 70:30, water in amount not in excess of about 40% based on the weight of said Portland cement, and, based on the weight of said copolymer, (a) 2-10% of non-ionic surfactant, (b) 1-7.5% of anionic surfactant, at least 15% of which is a sodium alkyl sulfate in which the alkyl group contains 9-17 carbon atoms, and (c) .[.1-5% of.]. polyorganosiloxane fluid surfactant, .Iadd.in an amount equal to about 2.5% of a polyorganosiloxane emulsion containing 29% of the polyorganosiloxane .Iaddend.the sum of (a) and (b) not exceeding about 14% by weight of said copolymer and the weight ratio of (a) to (b) being within the range of about 0.7:1 to 10:1.

This invention relates to additive compositions for modifying theproperties of Portland cement compositions and to the resulting cement,mortar and concrete compositions and methods for their manufacture. Morespecifically, the additive compositions to which the invention relatesare characterized by containing a copolymer of styrene and butadiene-1,3dispersed in water with certain minor amounts of non-ionic, anionic, andpolyorganosiloxane surfactants.

I have found that the use of the modified styrene-butadiene copolymerdispersions of this invention in combination with Portland cementgreatly improves various properties of cement-containing mixes. Thus incomparison with mortars and concretes prepared without the additive, themodified cement compositions of this invention require the use of lesswater to obtain standard flow and working consistency and the mortar orconcrete obtained has improved strength, especially when cured underadverse curing conditions, flexibility, adhesion, and elongation atbreak as well as smaller volume change.

The Portland cement additive compositions of this invention are, in moredetail, aqueous dispersions of a copolymer of styrene and butadiene-1,3having a styrene:butadiene weight ratio of about 30:70 to 70:30 and,based on the weight of the styrene-butadiene copolymer, (a) 2-10% ofnon-ionic surfactant, (b) 1-7.5% of anionic surfactant, at least 15% ofwhich is a sodium higher alkyl (i.e., at least nine carbon atoms)sulfate, and (c) 1-5% of polyorganosiloxane surfactant. Additionally,the amounts of non-ionic surfactant, (a), and anionic surfactant, (b),are regulated so that their sum, or total amount, is not more than about11% by weight of the styrene-butadiene copolymer and the ratio of (a) to(b) [(a):(b)] is about 0.7:1-10:1.

The concentration of styrene-butadiene copolymer in the cement additivecompositions of the invention can be varied widely as desired orconvenient, up to about 60% by weight of the copolymer, but care shouldbe taken, of course, not to have so much water in the additivecomposition that when added to a cement, mortar, or concrete mix toprovide sufficient of the additive, it at the same time introduces morewater than is needed to make a mix having desired flow and workingconsistency. In general, the additive composition is added in amountsufficient to provide in the mix from 5%-25% by weight of the copolymerbased on the weight of the Portland cement. Thus the additivecomposition preferably, contains from about 40% to 75% by weight ofwater, but in no event more than the amount which would provide in thecement or concrete mix greater than about 40% water based on the weightof the Portland cement.

The styrene-butadiene-1,3 copolymers employed in the compositions andmethods of the invention can be prepared in aqueous emulsion inaccordance with known procedures. For example, the styrene and butadienemonomers can be mixed in the proportions corresponding to thecomposition of the desired copolymer in water containing an emulsifyingagent or agents and heated with agitation in the presence of a peroxidecatalyst to initiate copolymerization. See, for example, Ryden U.S.Patent 2,498,712.

Some or all of the non-ionic and anionic surfactants employed in thecement additive compositions of the invention can be present whileeffecting copolymerization of the styrene and butadiene. Ordinarily,however, it is preferred to follow the practices used in makingstyrene-butadiene emulsions for use in preparing the so-called latexpaints. Thus some but not necessarily all of the anionic surfactant isintroduced to aid in effecting the desired dispersion and emulsificationin carrying out the copolymerization of butadiene and styrene, andnon-ionic surfactant is subsequently added to stabilize the resultingpolymer dispersion. The polyorganosiloxane surfactant and suchadditional quantities of non-ionic surfactant and anionic surfactant asare required to complete the cement additive composition aresubsequently introduced.

Illustrative of non-ionic surfactants are, for example: fatty acidesters such as glycerol monostearate, diethyleneglycol laurate,propyleneglycol monostearate, sorbitol monolaurate, and pentaerythritolmonostearate; acid derivatives of ethylene oxide products such as thereaction produc of six mols of ethylene oxide with one of oleic acid;condensation products of ethylene oxide with alcohols such as stearylalcohol; and condensation products of ethylene oxide with phenols,naphthols, and alkyl phenols such as octylphenoxynonaoxyethyleneethanol.Preferred are the condensation products of ethylene oxide with alkylphenols.

Illustrative of anionic surfactants are, for example: the alkyl arylsulfonates such as dodecylbenzene sodium sulfonate; sulfate derivativesof higher fatty alcohols (i.e., alcohols of at least nine carbon atomsand ordinarily not more than seventeen carbon atoms) such as sodiumlauryl sulfate; the sulfonated animal and vegetable oils such assulfonated fish and castor oils; sulfonated acyclic hydrocarbons; andthe like. As pointed out heretofore, at least 15% of the anionicsurfactant component of the cement additive of the invention should be asodium higher alkyl sulfate such as sodium lauryl sulfate and preferablythe anionic surfactant component consists of a mixture of an alkyl arylsulfonate surfactant and such sodium higher alkyl sulfate.

The foregoing and other non-ionic and anionic surfactants are disclosed,as are trade names and sources of supply for such materials, inMcCutcheon "Synthetic Detergents" (Macnair-Dorland Company, 1950).

Illustrative of the polyorganosiloxanes are the condensation productsresulting from polymerization of organo silane diols, as represented bythe formula ##EQU1## where R and R', in the above formula, representorganic radicals such as alkyl, aryl, aralkyl and alkaryl orheterocyclic groups, and n is one or more. Also useful arepolymerization products of organo silane diols in the presence of anorgano silane monol, and condensation products obtained from mixtures oforgano silane triols, diols, and monols.

Preferably the organo substituent of the siloxanes is lower alkyl (i.e.,methyl, ethyl, propyl), cyclohexyl or phenyl. Most preferably it ismethyl, and, accordingly, the preferred polyorganosiloxanes are thosewhich are condensation products of methyl silicols, and most preferablycondensation products of dimethyl silane diol.

Polyorganosiloxanes are commercially available in several forms whichare designated in the trade as "silicone fluids," "silicone emulsions"and "silicone compounds," the latter being siloxanes modified by theaddition of a small percentage of finely divided silica or other inertdivided solid. Any of these forms can be used in the practice of thisinvention.

The term "Portland cement" is used herein to include generally the kindof product obtained by heating lime-clay mixtures, or naturalcement-rock, to such a temperature that practically the entire productis sintered, followed by grinding. Various additives can be included, ofcourse, in accordance with conventional Portland cement manufacturingpractices. It will be understood, of course, that various modificationssuch as the hydraulic cements of the kind commonly known ascalcium-aluminate cements can be used in place of Portland cement assubstantial equivalents therefor in the compositions and methods of theinvention.

Cement mixes are made according to the present invention by simplyadding the cement additive of the invention to the cement with mixingand such added water as is necessary to obtain a cement mix of desiredflow and working consistency. If the cement additive of the inventionand Portland cement are to be employed in the manufacture of mortar orconcrete by admixture with a mineral aggregate, such as sand or amixture of sand with gravel, crushed stone or equivalent coarseaggregate, the cement will ordinarily constitute, in accordance withconventional practices, more than about 10% by weight of the mineralaggregate and usually from about 15 to 30% of the weight of the mineralaggregate.

The cement mixes of the invention can be applied as a paint forapplication, for example, to stucco, cinder block, cement block,plaster, concrete, wood, etc. The cement mortar and concrete mixes ofthe invention can also be flowed into molds or forms to provide, uponsetting, structures or objects of the kind for which conventionalcement, mortar and concrete mixes are now used.

While it is generally convenient to prepare the cement additivecomposition of the invention as a unitary product by pre-combining thestyrene-butadiene copolymer, non-ionic, anionic, and polyorganosiloxanesurfactants and then introducing the resulting mixture into the cement,cement-sand, or cement-sand-coarse aggregate mixture in making cement,mortar, or concrete mixes, it will be understood, of course, that it isnot necessary that all the various components of the additive be sopremixed. For example, equivalent cement, mortar, or concrete mixes areobtained by separate addition of the requisite quantity ofstyrene-butadiene copolymer emulsion containing sufficient of theanionic and non-ionic surfactants to avoid coagulation of the latex, thepolyorganosiloxane surfactant, and such additional non-ionic and anionicsurfactants as are necessary.

Compositions of the invention, methods for their preparation, andproperties of the compositions are illustrated by the following detailedexamples which are given in addition to the examples recited above.Parts and percentages are by weight unless otherwise specified.

EXAMPLE 1

The styrene-butadiene copolymer used in this example is of a kindmarketed commercially in the form of an aqueous emulsion for use inmaking what are now known as latex paints. The emulsion contains 47% ofstyrene-butadiene-1,3 copolymer, and, based on the weight of thatcopolymer, approximately 5% of the non-ionic surfactantoctylphenoxynonaoxyethyleneethanol, about 0.5% of the anionic surfactantdodecyl-benzene sodium sulfonate, and about 0.5% of the anionicsurfactant sodium lauryl sulfate. To prepare the cement additive of thisexample, there is added to this emulsion 2.5%, based on the weight ofthe copolymer, of sodium lauryl sulfate and 2.5% based on the weight ofthe copolymer of polymethyl siloxane emulsion containing 29% of thesiloxane. Thus the cement additive has the following composition:

                          Parts                                                   Butadiene-styrene copolymer                                                                         100                                                     Non-ionic surfactant  5                                                       Anionic surfactant    3.5                                                     Polyorganosiloxane    2.5                                                     Water                 119                                                 

A cement mortar mix is made by intimately mixing the above quantity ofcement additive with 500 parts Portland cement, 1500 parts sand (gradedstandard natural silica sand from Ottawa, Illinois, as described in ASTMspecification C-109-54T), and 41 parts water using the mixing methodidentified as ATSM designation C-305-55T "Mechanical Mixing of HydraulicCement Mortars of Plastic Consistency" and the standard mixing equipmentdescribed in said method.

The cement mix of this example is useful for preparing cement, plaster,floor topping, tank lining, sprayed concrete and the like for whichconventional cement mixes are commonly used and is particularly usefulfor patching and resurfacing of concrete roads, sidewalks and woodfloors. Various physical properties of the mix of this example and thecured product obtained therefrom are given in Table II hereafter incomparison with several products in which one or more of the additivecomponents are omitted.

The composition of the cement mortar mixes used for comparison with theproduct of this example are shown in Table I below. They are identifiedas comparative products A, B, and C respectively. The additivecomponents used in the comparative products B and C correspond incomposition to those employed in the product of this Example 1 of theinvention. The mixing method used in preparing the comparative productsis the same as that used in making the product of Example 1. Thequantity of water used is such as to give approximately the sameconsistency in all the mortar mixes.

                  Table I                                                         ______________________________________                                                       Comparative Product                                                           A      B        C                                              ______________________________________                                        Portland Cement  500      500      500                                        Sand             1,500    1,500    1,500                                      Water            275      212      140                                        Styrene-butadiene copolymer                                                                    --       --       100                                        Anionic surfactant                                                                             --       5        1                                          Non-ionic surfactant                                                                           --       --       5                                          Polyorganosiloxane                                                                             --       5        --                                         ______________________________________                                    

Pertinent physical data on the products described in this example aregiven in Table II. All such data except that relating to tensilestrength and elongation at break are obtained according to the ASTMmethods indicated in the table. Tensile strength is determined using anInstron tester. It is carried out at 25° C. using a one inch cube testspecimen from the center of a 1 × 1 × 6 inch sample, a recorder speed offive inches per minute, and a cross-head speed of .05 inch per minute.Instron Model TTB is used with a D-cell. The standard specimen holder ofthe instrument is milled to accommodate the test sample and expose theone inch cube between the jaws. The percent elongation at break isdetermined on the same instrument and in conjunction with the tensilestrength determination.

It will be seen in Table II that two sets of data are given for eachproduct under the several headings compression strength, flexuralstrength, tensile strength, and elongation at break. The cement productson which these tests are made are first cured for 24 hours at 25° C. andat 95-100% relative humidity. Certain samples are then kept at 25° C.and 50% relative humidity and tests made upon them, as indicated inTable II, after 7 days and 28 days, including the 24 hour initial cure.Other samples are immersed in water immediately after the initial 24hour cure and kept in water at 25° C. until tested, as indicated inTable II, after 7 days and 28 days.

                                      Table II                                    __________________________________________________________________________                     Product                                                                            Comparative Products                                                     of Ex-                                                                        ample 1                                                                            A    B    C                                             __________________________________________________________________________    Air Content of Mix (ASTM C-                                                   185-55T). Percent                                                                              13   8    13.8 40                                            Set Time (ASTM C-229-52T),min-                                                utes             170  250  150  --                                            Compression Strength (ASTM C-                                                 349-54T),lbs./sq.in.:                                                         (1) 25°C., 50% relative humid-                                         ity-                                                                            7 days         2,400                                                                              2,400                                                                              2,200                                                                              490                                            28 days         3,200                                                                              2,700                                                                              2,380                                                                              530                                           (2) in water-                                                                   7 days         2,300                                                                              2,300                                                                              2,180                                                                              205                                            28 days         2,700                                                                              2,800                                                                              2,775                                                                              245                                           Flexural Strength (ASTM C-                                                    348-54T), lbs./sq. in.:                                                       (1) 25°C., 50% relative humid-                                         ity-                                                                            7 days         920  460  370  225                                            28 days         1,490                                                                              570  510  225                                           (2) in water-                                                                   7 days         950  630  540  --                                             28 days         1,200                                                                              840  730  225                                           Volume Change (ASTM C-157-54T                                                 for 28 days at 25° C. and 50- rel.                                     humitity), Percent:                                                            Maximum Shrinkage                                                                             .03  .07  .05  .05                                            Maximum Expansion                                                                             .02  .05  .04  .09                                           Tensile Strength:                                                             (1) 25° C., 50% relative humid                                         ity-                                                                            7 days         400  190  275  74                                             28 days         660  240  373  85                                            (2) in water-                                                                   7 days         290  210  300  18                                             28 days         440  370  388  12                                            Elongation at Break, Percent:                                                 (1) 25° C., 50% relative humid-                                        ity-                                                                            7 days         .35  .12  .13  .38                                            28 days         .39  .06  .01  .61                                           (2) in water-                                                                   7 days         0.33 .13  .03  .58                                            28 days         --   .12  .07  .34                                           __________________________________________________________________________

It will be seen from the data in Table II that the product of Example 1,a cement composition of this invention, has greatly improved flexuralstrength and tensile strength over that of the comparative productsespecially when it is cured under adverse curing conditions.Additionally, it has greater stretchability than comparative products Aand B as indicated by the data on elongation at break, and exhibits lessvolume change than the comparative products. It is noted as acharacteristic of comparative product C that considerable air isentrained in making the mortar mix for that product according to thestandard mixing specification identified heretofore and it is believedthat the relatively low strength characteristics of the resultingconcrete are related to the air content.

.[.EXAMPLE 2

This example illustrates a cement paint composition of the invention.The styrene-butadiene copolymer employed in the paint is introduced intothe paint as an emulsion of the copolymer having approximately thefollowing composition:

                                 Parts                                            Copolymer (67% styrene and 33% butadiene                                                                   21                                               Anionic surfactant           .2                                               Non-ionic surfactant         1                                                Water                        20                                           

2 parts of a 25% solution in water of sodium lauryl sulfate and 1.7parts of a 29% dispersion in water of polymethyl siloxane are mixed in8.8 parts of water. The resulting mix is then intimately mixed alongwith the aforesaid styrene-butadiene emulsion and Portland cement togive a cement paint having the following composition:

                                 Parts                                            Portland cement              100                                              Styrene-butadiene emulsion-48% polymer con-                                   tent                         43                                               25% aqueous solution sodium lauryl sulfate                                                                 2                                                29% emulsion polymethyl siloxane                                                                           1.7                                              Water                        8.8                                          

The cement paint of this example is adapted for application to stucco,cinder block, cement block, wood, glass, metal, concrete, etc. andexhibits excellent adhesion..].

While the invention has been described in detailed examples withparticular reference to specific embodiments, it will be appreciatedthat no unnecessary limitations are to be understood therefrom. Theinvention is not limited to the exact details shown and described forobvious modifications will occur to those skilled in the art.

I claim:
 1. A cement .Iadd.mortar .Iaddend.composition comprising amixture of Portland cement, mineral aggregate, about 5%-25% based on theweight of said Portland cement of styrene-butadiene-1,3 copolymer havinga styrene to butadiene weight ratio of about 30:70 to 70:30, water inamount not in excess of about 40% based on the weight of said Portlandcement, and, based on the weight of said copolymer, (a) 2-10% ofnon-ionic surfactant, (b) 1-7.5% of anionic surfactant, at least 15% ofwhich is a sodium alkyl sulfate in which the alkyl group contains 9-17carbon atoms, and (c) .[.1-5% of.]. polyorganosiloxane fluid surfactant,.Iadd.in an amount equal to about 2.5% of a polyorganosiloxane emulsioncontaining 29% of the polyorganosiloxane .Iaddend.the sum of (a) and (b)not exceeding about 11% by weight of said copolymer and the weight ratioof (a) to (b) being within the range of about 0.7:1 to 10:1.
 2. Thecomposition of claim 1 in which the non-ionic surfactant isoctylphenoxynonaoxyethyleneethanol, the anionic surfactant comprises amixture of an alkyl aryl sulfonate and a sodium alkyl sulfate, at least15% of said anionic surfactant being a sodium sulfate in which the alkylgroup contains 9 to 17 carbon atoms, and the polyorganosiloxane fluidsurfactant is polymethylsiloxane.
 3. The composition of claim 2 in whichthe alkyl aryl sulfonate is dodecylbenzene sodium sulfonate.
 4. A cementcomposition comprising a mixture of Portland cement, about 5%-25% basedon the weight of said Portland cement of styrene-butadiene-1,3 copolymerhaving a styrene to butadiene weight ratio of about 30:70 to 70:30,water in amount not in excess of about 40% based on the weight of saidPortland cement, and, based on the weight of said copolymer, (a) 2%-10%of non-ionic surfactant of the group consisting of fatty acid esters,acid derivatives of ethylene oxide, condensation products of ethyleneoxide with alcohols, condensation products of ethylene oxide withphenols, condensation products of ethylene oxide with alkyl phenols, andmixtures of said non-ionic surfactants, (b) 1%-7.5% of anionicsurfactant from the group consisting of alkyl aryl sulfonates, sulfatederivatives of fatty alcohols of 9-17 carbon atoms, sulfonated animaloils, sulfonated vegetable oils, and mixtures thereof provided howeverthat at least 15% of said anionic surfactant is a sodium alkyl sulfatein which the alkyl group contains 9-17 carbon atoms, and (c) .[.1%- 5%of polymethylsiloxane fluid.]., .Iadd.about 2.5% of a polymethylsiloxaneemulsion containing 29% of the polymethylsiloxane .Iaddend.the sum of(a) and (b) not exceeding about 11% by weight of said copolymer, and theweight ratio of (a) to (b) being within the range of about 0.7:1 to10:1.
 5. A method for making a cement composition which comprisesintimately mixing Portland cement, mineral aggregate, a dispersion ofstyrene-butadiene-1,3 copolymer having a styrene to butadiene weightratio of about 30:70 to 70:30, water in an amount not in excess of about40% based on the weight of said Portland cement, and, based on theweight of said copolymer, (a) 2-10% of non-ionic surfactant, (b) 1-7.5%of anionic surfactant, at least 15% of which is a sodium alkyl sulfatein which the alkyl group contains 9-17 carbon atoms, and (c) .[.1-5%of.]. polyorganosiloxane fluid surfactant .Iadd.in an amount equal toabout 2.5% of a polyorganosiloxane emulsion containing 29% of thepolyorganosiloxane.Iaddend., the sum of (a) and (b) not exceeding about11% by weight of said copolymer and the weight ratio of (a) to (b) beingwithin the range of about 0.7:1 to 10:1.